Project description:‘Kuerlexiangli’ (Pyrus sinkiangensis Yu) is an important market pear in China. The shape and quality of the fruit is negatively affected by the presence of a persistent calyx. Here, to explore the molecular mechanism of calyx abscission, we designed an experiment to compare protein expression at two critical stages of the calyx abscission process under three treatments: a calyx abscising treatment (6000 × Flusilazole + 300 × PBO), a calyx persisting treatment (50 mg L−1 GA3), and a water control. We investigated the collected protein fragments using isobaric tags for relative and absolute protein quantitation (iTRAQ) to identify candidate proteins and perform relative quantification. We identified 378,078 spectra and 3,873 proteins, of which there were 2,371 differentially abundant proteins (DAPs) having Gene Ontology terms and associating with 124 defined pathways from the Kyoto Encyclopedia of Genes and Genomes. The DAPs that were correlated with calyx abscission were mainly those known to be involved in photosynthesis, plant hormone signal transduction, cell-wall modification, and carbohydrate metabolism. Quantitative real-time PCR was used to confirm the results of the digital transcript abundance measurements. Among the isolated candidate proteins, polygalacturonase and chitinase appear to play key roles during the process of calyx abscission. We identified candidate proteins that exhibit highly dynamic expression changes during the calyx abscission progress. These proteins are potential targets for future functional identification and should be valuable to explore the mechanism of the calyx abscission, and finally for the development of a method for inducing calyx abscission in fruit production based on the use of small molecules.
